Firing a pistol in an environment with no external forces

  • Context: Undergrad 
  • Thread starter Thread starter orthogonal1
  • Start date Start date
  • Tags Tags
    External forces Forces
Join the discussion
Registration is free. Ask a follow-up in this thread, or start your own.
2 replies · 2K views
orthogonal1
Messages
3
Reaction score
0
If one fires a pistol while holding it in one's hand, the pistol will exert a backwards force above the grip of the hand, causing the gun to both move backwards as well as exerting a torque, as the hand is essentially behaving as a fulcrum. If a pistol is fired in a gravity-free environment with no air resistance, and the pistol fires, and the backwards force occurs above the gun's centre of mass, will a torque be exerted and will the gun thus be made to rotate as well as move backwards?

This question is puzzling because nothing acts as a fulcrum aside from perhaps it's centre of mass(?)
 
Physics news on Phys.org
orthogonal1 said:
If one fires a pistol while holding it in one's hand, the pistol will exert a backwards force above the grip of the hand, causing the gun to both move backwards as well as exerting a torque, as the hand is essentially behaving as a fulcrum. If a pistol is fired in a gravity-free environment with no air resistance, and the pistol fires, and the backwards force occurs above the gun's centre of mass, will a torque be exerted and will the gun thus be made to rotate as well as move backwards?

This question is puzzling because nothing acts as a fulcrum aside from perhaps it's centre of mass(?)
A fulcrum is not required for rotation. A torque contributes to angular momentum regardless.

How about analyzing the problem with a free body diagram. One drawing to represent the pistol, the impulse from firing and the impulse from the hand. A second drawing to represent the pistol, the impulse from firing and no impulse from the hand.
 
  • Like
Likes   Reactions: Bystander
orthogonal1 said:
This question is puzzling because nothing acts as a fulcrum aside from perhaps it's centre of mass(?)
You are aware that spacecraft use reaction engines to change orientation for decades now?